The present invention is directed generally to feedback control circuitry for RF amplifiers, and is directed more particularly to a positive feedback control circuit for RF amplifiers.
RF solid state power amplifiers, such as those utilized in radar transmitters, require several stages of preamplification in order to provide sufficient gain in many applications. Considerations with the use of preamplification stages include reduced efficiency and additional complexity.
U.S. Pat. No. 4,709,215 discloses amplifier control circuitry that utilizes positive feedback to increase the effective gain of a traveling-wave-tube (TWT) amplifier. However, a consideration with the circuitry of U.S. Pat. No. 4,709,215 is the possibility of over driving the TWT when the gain of the TWT decreases with increasing input power.